Piston and rod connection



y 7, 1953 R. w. DOEG PISTON AND ROD CONNECTION Dec. 13, 1950 I INVENTOR, BY I69LP Matias 5, M Arraewev Patented July 7, 1953 PISTON AND ROD CONNECTION Ralph W. Doeg, Detroit, Mich., assignor to Nash- Kelvinator Corporation, Detroit, Mich., a corporation of Maryland Application December 13, 1950, Serial No. 200,653

6 Claims.

This invention relates generally to refrigerating apparatus and more particularly to assemblies of piston and connecting rods forming a part of said apparatus.

One of the objects of my invention is to provide an improved piston-connecting rod assembly of the type in which the piston and rod are universally connected together to compensate for slight misalignment and resultant undue wear and noise of the parts.

Another object of the invention is to provide an improved universalcoupling for a piston and connecting rod which makes practical the attachment of the coupling directly and solely to the piston to avoid objections inherent in attaching connecting rods by wrist-pins to piston skirts.

Another object of the invention resides in the provision of a flexible universal coupling for connectionto a piston to allow slight canting of the rod to the piston to compensate for misalignof my universal coupling and also functions to attach the universal coupling to the piston.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred form of the present invention is clearly shown.

In the drawings: 7

Fig.1 is a side view of a refrigerant motor-compressor unit embodying features of my invention and showing a portion thereof broken away;

Fig. 2 is a view shown in section of a pistonconnecting rod assembly embodying features of my invention, taken along the line 2-2 of Fig. 1;

Fig. 3 is another view in section of the pistonconnecting rod assembly, taken along the line 33 of Fig. 2;

Fig. 4 is a view in cross section of the pistonconnecting rod, taken along the line 4-4 of Fig. 2;

Fig. 5 is an isometric illustration of a part of the piston-connecting rod assembly, shown removed therefrom; and

Fig. 6 is an isometric illustration of another part of the piston-connecting rod assembly, shown removed therefrom.

Referring to the drawings by characters of reference, my invention is illustrated in connection with a refrigerant motor-compressor apparatus which comprises, in general, a compressor and an electric motor 2 2. These units are housed and sealed in a casing 24. The compressor 20 has a 2 cylinder block 26 provided with a horizontal bore 28 to receive a reciprocal piston 30, and the cylinder block 26 has suitable bearings for a vertical drive shaft 32, which is driven by the electric m0- tor 22. A crank 34, on the drive shaft 32, rotates in one end or strap 36 of a connecting rod 38 which is operatively connected at its other end to the piston by my universal coupling 39.

My universal coupling 39 comprises, in general; a rigid composite connecting member or coupling 40, a flexible coupling or diaphragm-clip 42, and a fulcrum member or rocker 44. The rigid coupling member 40 is connected rotatably to the rod 38; the diaphragm-clip 42 is attached to the piston; and the fulcrum 44 is interposed between coupling 40 and the diaphragm-clip.

To facilitate manufacture and assembly of the universal coupling, the rigid composite coupling member 40 is preferably made in two parts comprising a fulcrum member or wrist pin 41, and an extension member 48. The pin 41 rotatably connects the free end of the rod 38 to the rigid coupling member 4|] and the other fulcrum 44 pro vides for canting action of the rod relative to the piston in a plane transverse to the plane of rotation of the rod about the wrist pin. As shown, the extension member 48 preferably carries the fulcrum 44 although it will be understood that, if desired, the fulcrum 44 may be carried by .the diaphragm-clip 42. In either arrangement, the two fulcrums 41 and 44 are spaced longitudinally in the direction of reciprocation of the piston and co-operateto effect a universal action.

In the free end of rod 38, a bearing portion or transverse bore 50 receives the pin 4'! to connect the parts rotatably together and a bifurcating slot 52 in the free end of the connecting rod 38 receives the extension member 48 which fits snugly in the slot and has a cylindrical socket 54 complementary to the cylindrical periphery of pin 41.

As shown more clearly in Fig. 5, the fulcrum 44 in the form of a narrow fiat bearing surface is formed on the outer end of the extension mem-.

. J screw 62 to secure the diaphragm-clip 42 substantially centrally thereof to and flat against the adjacent end of the extension member 48, and also, I utilize the screw 62 to secure the coupling member parts, to wit: the pin 41 and extension member 48, rigidly together. Thescrew 62 extends through an aperture 65 in the diaphragmclip 42 and through analigning aperture 56 in the extension member 48 to thread into a tapped hole provided in the side of the pin 41. A head 68 on the screw 62 abuts the outer flat surface of the diaphragm 42 and is received in aclearance recess 1D in the piston. A shown, the relatively I large bearing surface 60 of the extension mem ber 48 locates within the outer'periphery of'recess to aid in allowing canting action between the piston and extension member or. to allow slight flexing of the diaphragm. The screw 62 is tightened down to clamp the parts together, and the inner end of the screw may project into the sleeve-like pin 41" and be :bent over, .as at -12; to lock the parts together.

The diaphragm-clip i2 is formed with a slight curvature so that when tightly held between the piston-and extension member 48, the. diaphragmclip will be tensioned and exert a force opposing lineal movement of the rod-38 away. from the piston'Sfi .in a direction normal thereto. A pair of radially spaced screws HIv are provided to attachthe diaphragm-clip 42- tothe piston 39 outwardly of screw 62 and cooperate with screw 62 tohold: the diaphragm-clip 42 under tension. The screws may be of .the so-called-sheet metal type of screw,- and the head of the piston may be recessed to receive the screw heads, as .illus- I trated in Fig.8. .The diaphragm-clip 42 may be formed of any suitable-resilient material, such as spring steel,- and the body of the. diaphragmclip maysbe substantially rectangular in shape and. have .end reinforcing'flanges 18. On its opposite side edges, I form the diaphragm-clip- 42 with oppositely disposed spring finger sockets 80 which are adapted to receive the end portions of the interrupted fulcrum M and oppose tendency of the extension member 48 to rotate about the axis of screw 62. In the present construction, the extension member 48 has tapered surfaces leading down from the fulcrum surfaces 44, and the-sockets 88 are formed complementary to said surfaces to provide close-fitting relationship between the parts.

.Inioperation,theifree'end' of .the rod 38 will rotate/about theaxis" of pin GLxand at thesame time, .the'rod .38, pin 41 and extension :member i42, 'as.a'rigid illllit, willicant' about .the' fulcrum 44. It will be understood that discrepanciesin alignment of the connecting rod. 38 and piston cylinder are usually small so that only a slight corresponding canting of the rod 38 is necessary to avoid binding of the parts. To effect slight canting of the rod 38 without binding and audible vibrations ofcontacting parts, the diaphragmclip-M is made to flex or deform slightly in the farea thereof adjacent the coupling flat surface '68 where screw 62 secures the parts together.

That is," a small-central area of thediaphragmclip flexes slightly to allow slight canting action of the rod while the fulcrum' l engages the fiat or unflexed portion of the diaphragm-clip by "straddling said flexing portion.

From the foregoing description .it will now be understood thatI have provided" an improved piston-connecting rod assembly in which a connecting rod is adapted to cant with, as well as rotate on, its bearing member or pin, and that such action is effected by attaching the bearing member at a single point of attachment to a ...tion. of .the piston skirt by press fitting wrist pins 'th'ereinto is eliminated and that the piston seal area which formerly extended from the piston headto the 'wristpin bore may now extend the 'full area of-the piston skirt.

Furthermore, by

. eliminating the wrist pin bore in piston sleeves,

the bearing area between the rod and piston may be increased-limited, of course, by the diameters of the pistons. In addition, I have provided a universal coupling I which -.allows pistons: to be made -inexpensivelyfor example, such was -.by screw machine operations.

Although only a preferred form of the invention has been: illustrated, and that form described indetail, it will'be-apparent to thoseskilledin the-art that various modiflcatio ns may bemade therein without departing from ;the spirit ofthe invention or from. .thescope. of the appended claims.

I claim: Y I

. 1. ma piston-connectingrod-assembly,a connecting rod end, a. coupling. ;memb.er. rotatably engaging said connecting rod- .end,..a.piston a plate member. interposed :between .said .coupling member and anadjacentdendof said pistongsaid plate member. being. formed withsa curvature, means securing said platelrnemberv adjacentits outer peripheryagainst saidjpist on end, .an-.abutment on said coupling -member inwardly of said securing means engaging against one sideof said plate member, .a recess insaid piston end overlying said abutment surfaceffulcrum means on saidv coupling member ofropposite sides of said abutment engaging said plate member outwardly of said recess, and a 'singlefastener securing said plate'member to said abutment and co-operaible with said securingmeans' to'tension said. plate member. flat againstjthe adjacent end of 'said piston.

2. In a piston-connecting rod assembly,-a connecting rod end, a piston, a socket member opposite said-connecting'rod end, a pin connecting said socket member rotatably to said connecting rodend, a. resilient plate againstpne end of said piston, securing meansattac'hing said plate to saidpiston outwardly. of the longitudinal axispf said. piston,. and .a "singlet fastener s'ecuring'ps'a'id plate, pin and socket'member'together and cooperating with said securing means to"; tension said plate.

3. Auniversal connection for use in connecting the free end of a connectingrod to a piston comprising, a coupling member for rotatable connection to the'freeend of the connecting rod a diaphragm for connection to the piston,'a:fulprum member on saidcoupling member fulcrume'd on said diaphragm at the center thereof, and a fastener attaching said diaphragmisolely at the center thereof to said fulcrum.

l. A universal connection for use in connectin the free end of a connecting rod to a piston comcoupling member, and a fulcrum on one of said members fulcrumed on the other of said members adjacent said single fastener.

5. A universal connection for use in connecting the free "end of a connecting rod to a piston comprising, a coupling member for rotatable connection with the free end of the connecting rod, a fulcrum carried by said coupling member, a flexible plate having one side engaging said fulcrum, a fiat bearing surface interrupting said fulcrum and engaging flat against the said one side of said flexible plate, and a single fastener extending through said flexible plate into said coupling member at said flat bearing surface to secure the flexible plate and coupling member together.

6. In a universal joint for connecting a piston to a connecting rod having a slotted end inter- References Cited in the file of this patent UNITED STATES PATENTS Name Date Houpert Apr. 3, Carrillo Dec. 3, Steele et a1. May 5,

Number Heusser June 27 1950 

